It is known that the lactic fermentation of alimentary products of animal origin (milk, meat) or vegetable origin (cabbage, olives, cucumbers, etc.) is a method used since time immemorial to conserve food. In this method there is provided that the lactic acid bacteria present in nature or suitably added to the raw material determine the fermentation of the present sugar thus producing organic acids. The lowering of the pH which follows causes the inhibition of several microbic species, thus increasing in this manner the hygienic-sanitary safety and the conservability of the food. In addition, the metabolic activities of the microorganisms responsible for the lactic fermentations determine the sensorial transformation of the raw material and the production of new and tasty food.
Among the products fermented on the basis of milk, yogurt is defined as the product obtained by coagulation of the milk without eliminating the serum, by the action of specific lactic acid bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) which are inoculated jointly in the milk and are found in the finished products alive and viable and in great quantity.
The metabolic activities of the two lactic acid bacteria inoculated in yogurt guarantee the conservability of the product, determine the specific organoleptic properties and influence the structure itself and the consistency of the yogurt.
In addition, both in yogurt and in fermented milks in which the addition of lactic microflora having probiotic activity, a role is recognized which may be defined of the “medical” type, due to the beneficial action which the added microflora may carry out with respect to the human organism.
The yogurt, in the several types, (classical, with fruit, to drink with different amounts of fats, etc.) is unquestionably an extremely wholesome and beneficial product and endowed with very rich properties from the nutritive point of view, due to the presence of proteins, vitamins and mineral salts.
However, in spite of the well known beneficial effects exerted by fermented milks, including yogurt, there are groups of people who, for a reason of diet or health requirements, may not use products based on milk of animal origin. In particular, the number of people who have allergies and/or have an intolerance to the proteins of milk or to lactose is in substantial increase and therefore they may not consume yogurt, even if yogurt could be beneficial for them.
In addition, it is know that the lactic fermentation of the raw materials of vegetable origin relates mostly to the production of sauerkraut, olives, cucumbers or other fermented green vegetables and there are many patent documents which describe specific methodologies and processes for the production of these foods. By way of examples, the following patent documents are mention: U.S. Pat. No. 3,932,674; French 2,770,973; CN 1,175,366; G.B. 2,234,661; U.S. Pat. No. 4,342,786.
Among the documents which relate to the fermenation of substrates of vegetable origin, there should be mentioned in particular the patents which describe particular processes capable of allowing the fermentation of a milk derived from soya or other vegetables with the following production of fermented curdled milks or products similar to cheese. In particular, the patent EPA 0988793 describes a process capable of allowing the production of fermented soya milk. In this process the soya milk is treated with a coagulating agent, it is pasteurized and subsequently it is inoculated with singular strains or mixture of strains which promote the fermentation process up to reaching a pH of 3.5-5.0.
The document WO-A-97/43906 describes a process which provides a fermentation phase to obtain a cheese, a curdled material or a yogurt starting from soya milk.
On the contrary, the patent EP-A-0500132 describes a process for the production of a curdled material starting from a soya milk, in which process being provided a phase of acidification obtained by addition of a chemical agent or lactic acid bacteria having fermentation activity.
Finally, U.S. Pat. No. 3,950,544 describes a process capable of allowing the preparation of yogurt from a soya flour.
A great part of these documents have the object of producing products which allow the consumer to obtain proteinaceous materials and other nutritional substances also for people who do not tolerate and/or are allergic to proteins of milk and lactose.
It should also be kept in mind that in addition to the people mentioned hereinabove, some consumers give up the utilization of milk and its derivatives also for ethical reasons because they do not take products of animal origin. It should also be noted that the organoleptic properties of all the products derived from soya and in particular the lactic products and yogurt are rather scarce and certainly not comparable to the properties of analogous products produced on the basis of animal milk.
In addition, the procedures for the production of these products are relatively complex and expensive. All these facts have resulted in a modest diffusion of the products mentioned hereinabove which are sold mostly in stores of vegetable products, microbiotic and similar stores and only in very small quantities in normal commercial establishments and, in particular, in supermarkets and hypermarkets.